Page 114 - Testing Electronic Components

An Optocoupler Symbol or Schematic

The optocoupler usually found in switch mode power supply circuit in
many electronic equipment. It is connected in between the primary and
secondary section of power supplies. The optocoupler application or
function in the circuit is to:

Monitor high voltage

Output voltage sampling for regulation

System control micro for power on/off

Ground isolation

If the optocoupler IC breakdown, it will cause the equipment to have low
power, blink, no power, erratic power and even power shut down once
switch on the equipment.

Many technicians and engineers do not know that
they can actually test the optocoupler with their
analogue multimeter. Most of them thought that
there is no way of testing an IC with an analogue
meter. Since we already knew the optocoupler pin
out from the schematic diagram, testing this IC is

just the same as measuring a normal bipolar
transistor and LED.

In order to accurately check optoisolator ic, you
need to use an analogue multimeter. Test the LED using the times 10k
ohms range. It should have one reading when checking both ways. If you

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